1. Field of the Invention
The present invention relates to organosiloxane polymers suitable for thin film applications. In particular, the invention concerns a novel process for producing high-silicon content organosiloxane polymers for thin film applications and to compositions containing such polymers.
2. Description of Related Art
There is a constant demand for decreasing the size of various features in semiconductor devices, e.g. integrated circuits (ICs). This demand creates challenges for the manufacturing processes. Photolithography is an example of a technique commonly used for the production of such devices and in particular for creating the patterns that define structures in ICs. In a lithographic process, a layer of a photoresist material is deposited on a substrate. The photoresist layer is selectively exposed to radiation, such as ultraviolet-light or electrons, and an exposure tool and mask are used for producing the desired selective exposure. The patterns in the resist are then created when the wafer undergoes a subsequent “development” step. The areas of resist that remain after development serve to protect the substrate regions which they cover. Locations from which resist has been removed can be subjected to a variety of subtractive or additive processes that transfer the pattern onto the substrate surface.
Usually, siloxane polymers for use in, e.g. spin-on applications are provided in the form of liquid composition containing the polymer having a modest degree of polymerization, for example a prepolymer having a molecular weight of about 1,000 to 10,000 g/mol, dissolved or suspended in an organic solvent.
The method by which the polymer is produced has an impact on the properties of the organosiloxane polymer, in particular on the use of the polymer composition for the production of thin films. Generally, a failure in the synthesis procedure will lead to a drastic reduction in the deposited film quality. Thus, to mention an example, high silixon dioxide content materials can be produced from tri- and tetraalkoxysilane monomers. However, these monomers readily produce high-molecular weight polymers that have a tendency of gelling during film formation or even during storage.
Therefore, there is a need for improving the synthesis methods of, in particular, high silicon dioxide materials to provide organosiloxane polymer compositions that give rise to high-quality thin films.